1. Field of the Invention
The present invention relates to a lens holder. More precisely, it relates to a lens holder having a cylindrical lens frame which holds at least one pair of lenses. The present invention also relates to a molding die assembly for molding the lens frame.
2. Description of Related Art
In a conventional lens holder having a cylindrical lens frame which holds a pair of lenses, the lens frame is provided on an inner peripheral surface thereof with an inner radial flange which separates the lenses at a predetermined distance. The lenses come into contact with front and rear surfaces of the radial flange so as to adjust the position of the lenses in the optical axis direction.
However, in the known lens supporting mechanism, the interior of the lens frame is divided into two circular regions by the inner radial flange. One of the lenses is accommodated in one of the circular regions and the other lens is accommodated in the other circular region. This results in a complicated structure for the lens frame. Consequently, when the lens frame is injection molded, it is necessary that the die has two sections that are moved apart from a portion of the dies that defines the flange (i.e., the die sections must be moved in opposite directions with respect to the flange). In such a molding process, the die sections tend to be eccentric due to limitations in the precsion of the process. Accordingly, the circular spaces for accommodating the lenses are not properly centered and the distance between the lenses are not stable. This molding process results in low optical precision. Furthermore, the process is expensive.